Specifications

Model 75A250A Manual Text
2-7
REV A
2.2.2 Remote Operation (continued)
2.2.2.7 RS-232 Communications (continued)
Table 2-3
RS-232 Connector Pin-Outs
Pin No. Signal Data Direction* Description
1 DCD < Device Carrier Detect
2 RD < Receive Data
3 TD > Transmit Data
4 DTR > Data Terminal Ready
5 GND N/A Ground
6 NC N/A No Connection
7 RTS > Ready To Send
8 CTS < Clear To Send
9 NC N/A No Connection
*Note:
> = Output from Model 75A250A
< = Input to Model 75A250A
Special Note: A null modem cable or adapter is required in order to properly interface the
Model 75A250A to a standard serial port on a computer.
Once the RS-232 interface is established, commands are processed in the same manner as that of
the IEEE-488 interface. The command structure is identical, except that there is no EOI line.
Therefore, all commands are terminated with a line feed (<LF>). Since this is a full-duplex
asynchronous interface, if the Model 75A250A detects an error, the error message is immediately
transmitted to the host controller. These error messages are defined in Table 2-2.
2.2.2.7.1 RS-232 port settings
The RS-232 port settings used for communication with the Model 75A250A are as follows.
Word Length: 8 bits
Stop Bits: 1
Baud Rate: 1200–76,800 (switch-selectable)
Parity: None
2.2.2.8 Remote Commands
The following commands are available to the user for remote communication and operation of the
Model 75A250A. In the descriptions of these commands, a lower-case “x” is used to signify a
numeric value or parameter.